This invention relates to the field of sound baffling devices, and more particularly the use of an enclosure containing a vacuum to baffle sound, as well as the various practical uses to which this invention may be put. Some other improvements which aid the invention in operation are also shown.
Sound baffling devices have been used in the past to modify acoustics and to reduce the ambient noise reaching the ears. Such uses have included acoustic baffles for lecture halls and theatres, sound proof partitions to reduce the ambient noise, and the sound baffling cups of ear protectors. The means whereby these previous sound baffling devices achieved these results were essentially through sound deflection or sound reflection, and through sound absorption.
Many previous sound baffling devices also may have had no facility for dynamically adjusting the ambient sound. If such facility was present, it may have involved a change in the spatial disposition of the sound baffling devices. The ability to dynamically alter the inherent sound baffling characteristics of sound baffling devices may not have been shown previously.
For sound absorption, cellular plastics were often used. These plastics have shown various spectral sound absorption characteristics. In general these plastics were comprised of either whole or fractured cells containing air. Hence these plastics were also capable of some sound transmission. However, although these plastics could be used as fillers, most auspiciously in the cavities of buildings, they do not appear to have had any previous use to baffle sound in this way.
In spite of the materials previously available, some previously known devices did not use sound baffling, even when such use would have been beneficial. In head phone sets, sound baffling cups were not used to baffle the ambient noise, even though transmitted noise considerably reduces the audibility and perceived rendition of the rendered sound.
Some previous ear protectors used sound baffling cups having openings which were elliptical or circular and resident in one plane. This, while workable, does not take into account the curves of the human body surface, and the fit is therefore less than optimal.
Some previous devices also used a semicircular fitting means which relies on elastic tension to hold the sound baffling cups against the ears. Because of the spatial requirements of the semicircle some head gear may not be comfortably worn when this type of fitting means is used.
Also, most previous head phone sets generally used a Y shaped wiring arrangement to reach the speakers of the respective ears. This wiring arrangement is less than optimum as it can interfere with the movement of the head and neck.
In most previous devices, the connection to the playback unit is made by means of a wiring arrangement to a plug-in connector which resides in the playback unit. If the connecting means of these devices is snagged, the connection has a tendency bind fast in the playback unit plug-in connector, thereby allowing considerable stresses to be applied to the connecting means.